A Big'un - the Audio Nirvana Super 15

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The pioneers of audio used 2x4 framing, bracing with 3/4" thick exterior grade plywood for cinema false wall baffles and is still the recommendation ~ a century later, so is what I've historically done. For lower SPL [mid] bass, double thickness 3/4" MDF or braced 19 mm void free plywood should be fine.

GM
 
Read all 40 pages just bought 3 an cast 15's and 2 cast 8's these will be behind a false screen wall with drivers around 3 ft from back wall I want some serious movie theatre sound. 5.1 on my pioneer avr and for critical listening 2 channel on my Nelson f5. Thinking after reading your thread about doing open baffle phy hp style. But was wondering how critical the front baffle strength will need to be any thoughts would much appreciated

Hey - sounds like this is going to be a serious system :cool:

First off, the 15" drivers are not light, they are going to benefit from a strong baffle for mounting them securely. And although I've never tried them in anything but a very strong box I wouldn't advise anything other than a substantial, solid baffle.
 
I had a chance to borrow back a pair of A10.3 Pencil's I had built last year and have now thoroughly broken-in. I spent a few weeks with the Pencil's instead of my Big'un (which takes up permanent residence in my family room). Source was a Magnum Dynalab FM tuner playing through a tube amplifier (single ended 6AS7).

I think most people have heard about the A10.3 in the Pencil and how well they perform, their clarity, wide dispersion, clean treble and really deep bass. I can also attest to how well they image.

I was interested to listen to the A10.3 again as I've been considering building one for myself again, perhaps to use instead of the Big'un. The A10.3 has more coherence in the treble because it doesn't need to use a whizzer cone like the AN15 and I can hear this. But the surprising thing is, I 'missed' the Big'un AN15.

For casual listening, the Big'un has more life to my ears, it makes music in a way that the Pencil's did not. I don't know why, I don't think it's the AN15 driver alone that makes this impression as I feel the A10.3 is the better driver in may regards, I think the open back box is a critically important factor here and that may not be a good thing for imaging if you listen mostly in stereo (remember the Big'un is a mono speaker).

I was surprised enough at what I found, that I wanted to share my thoughts here.
 
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Welcome to my 'world'. ;) Step up to a ~full range compression horn system and the 15s will sound way more 'wanting' to them than this comparison. Reproducing 'life' requires way more than most folks realize.

At the very least it 'sounds' like maybe a stereo pair of OB A10.3 blended to the mono AN15 would be worth experimenting with.

GM
 
Trouble with a horn system (FLH) is the size. The AN15 box is already large, but horns are even bigger and will stick out into the room. Vertical height is easier to use, but that means BLH. Mind you, I do prefer mono, so only one set of horns needed.

I'm not sure the A10.3's have enough oomph for use in OB like the AN15 - maybe the A12P has more size and sensitivity.
 
Understood, just trying to give you an idea of what you're still missing [for better or worse depending on the recording] since you now have what you consider a good frame of reference in the A10.3. Not being familiar with them, I didn't realize its efficiency was so abysmal that it would cause too much baffle step loss.

WRT a BLH, the 'step up' would be negligible unless a front WG is used also and even then the compression horn system would still be up to ~12 dB more efficient depending on the 'FR' driver used. One need only do a 6-12 dB wide band level boost [or cut] to a speaker system to hear how much distortion [or detail lost] can make to a recording due to system efficiency.

GM
 
My knowledge of horns is severely lacking, it would be good to go and hear one so I know what it 'sounds like'. But from what I've read, it's difficult to get full range from one horn, so you end up needing two or three horns with the added complication of cross-overs or multi-amping and so this is a level of effort I'm a bit nervous of :)
 
can there be cheating with front horns by limiting the lower horn's cutoff to around 70Hz and still get the vibe? - lets say a good 12" in RCA-Fan's 70Hz plus mid and treble horns augmented by bandpass for 30->80 or 90Hz? I still have Bruce's "Monolith" which goes to around 40Hz and would make a nice helper woofer to two Karlson 10.

with a D120, the little 70Hz horn in its passband is ~10dB more sensitive than a Fostex 8 in large BLH
70hz5.gif


does Guide-sound limit the magnet size on their larger FR for sonic reasons? - the 15 could use a stronger motor for Karlson or Karlsonator.
 
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I'm not yet convinced, so ultimately I'd have to hear one. I realize horns done well have excellent impulse response and high sensitivity but they don't do what an open back box does - which is to better avoid coupling to room modes at LF and to provide 'ambience' from front/side wall reflections. This last point may be key to the liveliness I hear from the Big'un AN15.
 
........so this is a level of effort I'm a bit nervous of :)

Don't blame you and why I figure that if one must have XOs, then go ahead and step up to a compression loaded system and now that Tom Danley has worked out the way to 'have our cake and eat it too' with his Synergy concept, this is the only way I'm interested in nowadays. Unfortunately, it's currently a physically deep solution, so not for small[er] rooms.

GM
 
you will have a hard time going to crossovers, unless it is a 6db slope.
I love good horns, but won't make the room for a 3' deep bass horn.
Yet I'm still here on this forum.
Even after an 8" b20, array of 9 x 4", and 12" full range philips (phy open baffle).
I'm currently interested in 8" for under the tv (movies), or I'll get the box built for my an10 and massively eq it to tameness.


After so much time with a full range driver, everything else can seem off.............
 
there was some treble roughness of the old Nirvana stamped frame Super10 when placed in the Karlsonator 12 which I think might be tamed with a couple of small pieces of felt on the inside of the wings - its even rougher as a direct radiator and the K-variant the best I've heard for it - same for 12LTA in the Karlsonator 12 - 12LTA is devoid of much HF energy so no damping would be needed. Might give the little 70Hz Bill Woods horn a go. My K-horns sound terrible. Sentry IV might almost work for midbass but no space to setup. Glad overall I stuck with Karlson and K-tube. btw, on the 6dB electrical slopes, I think that's why David Dicks just runs a highpass cap on coax - its rough but in a way that emulates the Nirvana FR sound. (a swamping resistor across the compression driver can be useful)
 
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Some of the treble curves for the smaller AN drivers look scary rough. I picked the AN15 because it looks much better and I remember Bud Purvine saying that the whizzer was very well designed, almost a 'horn' flare back to the voice coil. I have also modified it (as described somewhere earlier in this thread) and eventually hope to go the whole hog and implement Bud's eNable decorations on the cone too. It is a surprisingly good sounding driver although the only FR units I have had to compare it with were an FE127E, EL70, A10.3 and a small 3" unit I used in my Martello speakers.

The Synergy horn has caught my interest many times. I really like the concept, I think its the most compelling approach. But it's a challenging DIY build and there really isn't enough collective experience out there - I will be interested when there is a well worked out DIY design with good listening reports (e.g. no treble harshness) and an easier way of making one.
 
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Sorry, no measurement capability. My comments were referencing the published curves from the manufacturers website. I've not seen any off-axis plots but I can say from listening that the dispersion is pretty good - you can sit anywhere in the room. Of course, driver does not have a flat dispersion behaviour over all frequencies. The whizzer does a good job of ensuring treble is heard off-axis but I think the treble is a little hotter when listened to directly on-axis than when listened to off-axis.
 
Hi there fellow diy:ers!
I just finished building the 13.6 cu ft bass reflex cabinet for my AN15 Alnico's, the largest cabinet recommended by the manufacturer. I am very pleased with the overall representation in these cabinets, especially the bass output. I get solid bass down below 30 Hz. I have confirmed this quite a few times by now with a spectrum analyzer. Here is a video showing a vocal number (no bass to speak of in this video, but I've uploaded some other videos with more bass). Needless to say, the camera microphone doesn't do the speakers justice. But I think it gives a hint of the sound and it shows the setup and the used gear. Cheers!
https://www.youtube.com/watch?v=0qgMrEYf-eM
 
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